When mowing a lawn or other vegetation area, it is desired to cut the greatest width possible, as well as with the sharpest, or most robust cut. Conventional push or driven mowers, as well as the ROBOMOW® Classic™ autonomous lawnmower, available from Friendly Machines, Even Yehuda 40500, Israel, and detailed in “Robomow Installation & Operation Guide”, ©1999, this document incorporated by reference herein, typically employ bodies with cylindrical or rounded blade hoods, that envelope a single rotating blade therein. The ROBOMOW® Classic™ autonomous lawnmower has a blade housing and blade assembly in accordance with that detailed in PCT patent application No. PCT/IL99/00336 (WO 99/65289), entitled: CUTTING AND MULCHING BLADE AND DEVICE, this PCT patent application incorporated by reference herein.
All of these mowers have a body with an area, preferably circular, for accommodating a single rotating blade. These blades typically include an opening though which a rod from the rotating motor extends. This rod is adapted to receive a bolt or the like at its end, to retain the blade in the assembled position for mowing (cutting). The blade length is less than the diameter than the blade hood for proper operation of the lawn mower.
This single blade construction exhibits drawbacks. Initially, the length of this single blade requires an equal cutting length (as well as an equal cutting width), whereby the length of the mower is fixed at least by the length of this single cutting blade. Also, this single blade is rotated by the motor at a single speed, and should there be high grass, dense grass, dense vegetation or combinations thereof, the blade rotation will slow down and cutting speed will be slower, resulting in a less sharp or robust cut.
Moreover, in multiple blade mowers, these blades are typically connected by a single belt and driven by a single motor. If a high resistance is applied to one of the blades, such as in dense grass or vegetation, this one blade slowing down affects all other blades and forces them to slow down as well. Again, the blade rotations will slow down and cutting speeds will be slower, resulting in a less sharp or robust cut.
All of the lawnmowers mentioned above exhibit additional drawbacks in that their blades are attached to a rotating rod by a bolt or other similar screw-type mechanism. This is because disassembly and reassembly of the blade onto the rotating rod requires special tools, is time consuming and may be dangerous. Moreover, when the blade is reassembled onto the rod, it may not be assembled so as to be balanced, due to wear on the opening and improper positioning by the person doing the reassembly. Also, the blades may be attached too loose or too tight, whereby the blade could come off, if too loosely attached, or could fail if too tightly attached.